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Plants Multiply . . . But How Do They Add?

Brookhaven Lab shows how rapeseed plants ‘balance the books’.

At some point – usually near the end of the month – practically everyone has to face the hard facts of math: Of paying their bills and hoping that somehow, a few positive numbers will carry over into the following four weeks.

In a sense, plants face similar challenges. While they aren't known to do double-entry bookkeeping (the absence of thumbs makes it tough to carry the ones), they do have to adapt to changing environments, and ‘decide’ which limited resources to allocate where, and when. Those choices are of interest to Department of Energy (DOE) scientists, since some plant products can be used as both foods and fuels.

Scientists at Brookhaven Lab have identified key elements in the biochemical mechanism plants use to limit the production of fatty acids.

Recently, researchers at the Office of Science's Brookhaven National Lab (Brookhaven Lab) took a look at rapeseed, best known as the source of canola oil and meal. Canola oil is popular in the kitchen, but it's also an important industrial feedstock and source of biodiesel fuel. And canola meal – taken from the protein of the plant – is a significant animal feedstock, consumed by cattle, fish and fowl and even racehorses.

So how do rapeseed plants ‘balance the books’ between oil and protein: Between making more of one or the other at a given moment?

That's what Brookhaven Lab scientist Jorg Schwender and his postdoctoral research associate Jordan Hay looked at, using computer modeling (a technique called "in silico", as opposed to in the glass of the lab, in vitro, or in the living critter, in vivo). Specifically, they designed a complex silicon simulation incorporating the nearly 600 chemical reactions that play an important role in the plant's metabolism and seed oil production. They also plugged in information on which reactions happen together, and where they occur in the rapeseed's cells.

The scientists then crunched the numbers, and used the model to see which sets of biochemical steps – catalyzed by cellular machines called enzymes – could have a big impact on the plant's ‘budget,’ leading it to either produce ‘low oil’ seeds and therefore more protein, or ‘high-oil’ seeds and less protein. They found 149 reactions that could affect the production of protein, and another 116 that might impact the production of oil – including a number that hadn't previously been seen as potentially significant.

Developing embryos after being excised from a growing rapeseed plant. The embryos accumulate seed oils which represent the most energy-dense form of biologically stored sunlight, and have great potential as renewable resources for fuel and industrial chemicals.

Why is this significant? After all, aside from horrible Halloween horror movies, plants are rarely a problem for people. But people can manipulate plants through breeding and genetic engineering. And changing cellular machines – by altering plant genes – allows researchers to produce plants that make more of a desired end-product.

That's what the silicon simulation at Brookhaven Lab has done: It's given researchers a better sense of which rapeseed genes to modify in order to produce plants that might yield either more protein or more oil. That, in turn, could show the way to the production of more food and better fuels, which will make for better bottom lines across the board. And that's the Office of Science at work, silicon simulations in service to citizens.

The Department's Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information please visit http://science.energy.gov/about. For more information about BNL, please go to: http://www.bnl.gov/world/.